GMAT考试句子改错习惯用语高频考点分享

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　　while at the same time的用法
　　考点分析：
　　原句是and at the same time，有的选项只有at the same time，有的选项是直接用while
　　类似考题(Prep语法笔记旧-130题) Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.
　　A. while at the same time they have introduced some 100,000 dangerous chemical pollutants, having

　　B. while at the same time introducing some 100,000 dangerous chemical pollutants that have
　　C. while they have introduced some 100,000 dangerous chemical pollutants at the same time, and have
　　D. but introducing some 100,000 dangerous chemical pollutants at the same time thathave
　　E. but at the same time introduce some 100,000 dangerous chemical pollutants, having
　　(答案：B)